Effect of mild thermal treatment on the polymerization behavior, conformation and viscoelasticity of wheat gliadin

The physicochemical properties of gliadin upon mild thermal treatment were studied in terms of polymerization behavior, conformation and viscoelasticity. Gliadin samples were heated at 40, 60 and 90 degrees C for up to 20 min. Results showed that alpha-gliadin started to polymerize via disulfide (SS) bonds before gamma-gliadin at 90 degrees C, resulting in the extractability loss in aqueous ethanol. beta-Turn and specific beta-sheet structures were partially conversed to alpha-helices during thermal treatment. Rearrangement of noncovalent forces might contribute to viscosity loss of gliadin at 40 and 60 degrees C. However, the elevated elasticity at 90 degrees C was mainly due to gliadin polymerization while the viscosity variation was resulted from combined effects of non-covalent forces and covalent SS bonds. This study could offer insight into the variation of gliadin characteristics during the early baking process. (C) 2017 Elsevier Ltd. All rights reserved.